Shank collar for boring



I 1,989,171 DRILLING, PUNCHING, AND LIKE ES FOR ATTACHING THE SAME Jan.29, 1935. H. KCHLEN SHANK COLLAR FOR BORING,

TOOLS, AND IN APPLIANC Filed March Patented Jan. 29, 1935 UNITED STATES.

SHANK COLLAR FOR BORING, DRILLING,

PUNCHING, AND LIKE TOOLS, AND IN AP- PLIANCES FOR ATTACHING THE SAMEHans Kiihlen, Rosslau, near Dessau, Germany,

assignor to the firm Flottmann Aktiengesellshaft, Herne, GermanyApplication March 29, 1934, Serial No. 718,091 In Germany February 20,1933 2 Claims. (01. 121-32) age of the tools, and affect in particularthe collars at the neck of the tools where heavy impact occurs. Theimpact of the collar, particularly in the case of hollow borers anddrills, results in distortion of the fibre of the metal, and breakagefrequently results at the thickest part of the tool, where the collar isapplied. Various methods of heat treatment, toughening and hardening hasbeen tested for overcoming this defect, without striking success. Theuse of rubber collars held by clamps is one of these methods, but rubberis' not a material well adapted by its general properties to use in thisconnection, and secure attachment by clamping is difiicult to efiect.Welding, which has also been proposed, has the defect of involving adegree of heat which is deleterious to the metal, particularly in thecase of some alloy steels, and welding does not provide a particularlystrong joint. Shrinking the collar on to the neck of the tool, into ashallow depression forming a seat therefor, involves weaking the toolshank. It is well known that even a comparatively minute impression madein the surface of tool steel, as for example an impression of the makersname, or a number, results in quite substantial weakening of the steel.

According to my invention these difiiculties and defects are overcome byusing for the collar a coiled metal spring, generally of spring steel,the normal internal diameter of the spring being somewhat smaller thanthe diameter of the neck of the tool. By diameter of the neck I mean, asthe case may be, the diameter of a cylindrical neck or the diameter of acircle within which the outline of a polygonal neck is inscribed. Thespring is expanded for placing it on the neck, and grips the neck firmlyon contraction. A secure and permanent hold is thus secured, withoutrequiring machining to make a seat for the spring, though of course thespring might be applied to a machined seat in cases where the provisionof such a seat does not involve undue weakening. No heat treatmentliable to weaken the structure of the metal is required.

To enable the collar to serve also as a resilient cushion or buffer thecoils at one or other of its ends may be given an enlarged diameter andpitch, allowing of axial compression.

For conveniently applying the collar to the tool the invention includesan appliance comprising two members pivotally connected by a knucklehaving a concentric socket for the spring, with two dogs, one on eachmember, for engaging respectively the ends of the spring and expandingthe same by rotation of either member, the diameter of the socket beingsomewhat larger than the normal diameter of the spring.

A tool with a collar according tothe invention is shown by way ofexample in Fig. 1 oi the annexed drawing, the collar being shown insection. An appliance for applying the collar according to the inventionis shown in Figs." 2 and 3, Fig. 3 being a side view, showing the devicein section, with the spring in the socket and the tool insertedthereinto.

In Fig. 1 or represents the tool and b the coiled metal spring collar,consisting in the example shown of .wire of circular cross-section, butwire of any other convenient cross-section may be used. Two coils b atthe right hand end of the spring, facing the bitt, are of slightlyenlarged diameter and pitch to allow of axial compression, the othercoils lying closely together.

The device shown in Figs. 2 and 3 has a cylindrical socket c for thespring, with an opening at the base so that the tool can be pushedthrough it. The socket is formed by a hollow boss at one end of an armi, and this boss is embraced'by an eye e at one end of an arm f,connected to the boss by a screw engaging into a circumferential groove,which allows rotation of either arm in relation to the other. Within thesocket, on the arm i, there is a dog 01 for engaging the inner end ofthe spring, and a dog h for engagingthe outer end of the spring is fixedto the arm f by a screw 9. The dog it is removed for inserting andremoving the spring.

By rotating either of the arms in one direction the spring is radiallyexpanded and the coils are thus pressed evenly against the wall of thesocket. The tool can then be inserted easily, whereupon the spring isallowed to contract upon it.

What I claim is:

1. ,A shank collar for boring, drilling, punching, picking and liketools, consisting of a coiled metal spring whose normal internaldiameter is somewhat less than that of the tool shank which it embraces,and wherein the coils at one end of the spring are of enlarged diameterand pitch, allowing of axial compression for producing a resilientbuffer efiect.

2. A boring, drilling, picking, punching or like tool as claimed inclaim 1, wherein the coils at one end of the spring are ofenlargeddiameter and pitch allowing of axial compression for producing aresilient buffer effect.

HANS HLEN.

